Offshore wind energy has long been seen as an expensive way of generating power, costing about two to three times more than erecting turbines on land, but the expense is likely to come down, while the costs of nuclear energy are opaque, according to analysis by the European commission.

The nuclear crisis in Japan has led the UK, France and other countries to tell their nationals to consider leaving Tokyo, in response to fears of spreading nuclear contamination. The crisis also prompted the EU's energy commissioner, Günther Oettinger, to say: "There is talk of an apocalypse, and I think the word is particularly well chosen."

"There are 143 nuclear power plants in Europe and they are not going to disappear," she said. "But when it comes to new energy capacity that discussion is likely to be very much influenced by what is happening in Japan."

However, she was careful to insist that it was up to member states to decide on their energy mix, as long as they adhered to the Europe-wide targets of cutting greenhouse gas emissions by 20% by 2020 and generating 20% of energy from renewable sources by the same date.

Hedegaard published a "roadmap to 2050" this month that showed the EU was on track to reduce greenhouse gas emissions by 25% if current policies are implemented. She said this strengthened the case put by some member states that the EU's current target of cutting carbon dioxide by 20% by 2020 should be toughened to 30%.

China and Germany have put nuclear projects on hold after the incidents at several Japanese nuclear reactors.

Europe's biggest nuclear operator, EDF of France, insisted that plans to build a new generation of reactors in Britain should not be held back by the problems in Japan.

Vincent de Rivaz, chief executive of EDF Energy, said: "While we understand the importance of adjusting the timetable to take into account the Nuclear Installations Inspectorate report [on the Japanese crisis], it is also equally important that establishing the framework for new nuclear should not be subject to undue delay. The events in Japan do not change the need for nuclear in Britain."

He said meetings this week with local authorities regarding places such as Hinkley Point in Somerset, where EDF wants to build a new reactor, had still been positive.

De Rivaz told the Nuclear Development Forum, including the energy secretary, Chris Huhne, that there was "local determination to press ahead with our project, and the strong feeling that whilst we should learn any lessons we may need to from Japan, we should not delay our progress".